U.S. Pat. No. 3,993,002 issued Nov. 23, 1976 discloses a shelf arrangement in which uprights are arranged so as to support a pair of brackets to which a shelf structure is secured. This patent does not disclose an extendible shelf.
U.S. Pat. No. 3,403,789 issued Oct. 1, 1968 discloses a hingedly mounted shelf arrangement in which a pair of shelf elements are arranged so that one element may be extended outwardly thereby to increase the shelf area.
U.S. Pat. No. 3,612,288 issued Oct. 12, 1971 discloses a plurality of hingedly connected panels interposed between layers of packaged items so as to impart stability to the overall stack of items.
None of the above patents discloses a pair of primary brackets which respectively are cooperatively associated with a pair of secondary bracket elements and arranged to form an extendible structure which is adaptable for use as a single display unit or which may be employed as a component of a single display stand or of an end or intermediate stand constituting one of a series of display stands arranged in side by side relationship.